Quota reporting UI is broken in files app with APCu caching enabled

[jonas2515]

With php APCu caching enabled in nextcloud, the quota/used-storage reporting UI in the Files app is broken.

Steps to reproduce:

1. Open Files app
2. Upload a file with a known size
3. Reload page or click on the quota UI in the bottom of the left sidebar to reload it.
4. The used storage shown in the UI hasn't changed

Removing a file works to reproduce as well.

The used storage is updated after restarting php-fpm on the server and then reloading the page. That's because restarting php-fpm clears the APCu cache.

Disabling the APCu cache fixes the bug, now the storage is updated immediately after adding/removing files.

Tested with apache + php-fpm 8.3.17, and Nextcloud 31.0.1, as well as Nextcloud 30.0.7

[jonas2515]

When reproducing, make sure to disable the browser cache, as there's a second bug interfering with this: #51586

[joshtrichards]

This is expected behavior. The storage usage, in this context, is cached for 5 minutes both in memcache (#32048) and, more recently, by the front-end as well (#45957).

Related: #33553